Aging skin is the result of more than just chronological age. Skin is exposed to environmental elements that cause radicals to form in the skin. These radicals attack the collagen layer of the skin and break it down, causing lines and wrinkles to appear. This process is commonly called photo-aging. Diseases and disorders of skin that also may result from radical damage include skin cancer, skin irritation or inflammation, dermatitis, allergy, psoriasis, acne, eczema, rosacea, and radiation exposure.
Application of antioxidants can help prevent radical-induced damage in skin. Applying Vitamin C, for example, to the skin can provide antioxidant protection, prevent photo-aging, and stimulate collagen production. However, not all Vitamin C formulations produce these benefits due to lack of stability.
Numerous approaches to achieving a stable formulation of ascorbic acid include micronization (PCT publication No. WO 02/019972 to Vivier, G.), low pH (U.S. Pat. No. 5,140,043 to Darr, D. and Pinnell, S.), formation of suspensions or dispersions, lowered water activity, addition of various carriers, and derivatization, in particular, esterification. Regardless of the approach, these methods generally are inadequate to prevent degradation of ascorbic acid for long term storage, for example, for a period of one year at room temperature. Derivatization, while assisting in preventing degradation, for example, also may cause a decreased activity.
The challenge of achieving stability while maintaining activity of ascorbic acid compositions is addressed by the present inventors.